During the quest "The Tower Outta Nowheres", Geralt encounters a wizard trapped behind a magical door inside a tower. The wizard claims he was trapped there by the tower's Defensive Regulatory Magicon (DRM), which locks down the tower if anyone but the original owner tries to enter it. The tower's previous owner wrote a treatise on how to remove the defenses called "Gottfried's Omni-opening Grimoire" (GOG).

The initials "DRM" are a reference to Digital Rights Management, which is used by game publishers and platforms to prevent a game's original purchaser from freely sharing digital copies of it over the internet. The initials "GOG" are a nod to the website Good Old Games, which was founded in 2008 by The Witcher 3's publisher CD Projekt. It's famous for selling DRM-free copies of games and other software so that users may freely backup and share what they purchase.

Later on, while Geralt and the wizard are escaping, the defense system notes "disturbing indications of freedom". This is likely a jab by the game's developers at aggressive DRM policies, and echoes a common criticism that DRM restricts end users from freely controlling the software they purchase.
Video